1. Field of The Invention
The invention relates to contacts for use with an IC memory card, especially to a female or receptacle contact including at least three beams wherein each has variant cross-sectional dimension along its length for corresponding to the stress variation thereof, such that the entire beam bears a generally uniform stress along its length when a pin male contact is inserted into the female contact.
2. The Prior Art
As shown in FIG. 1, the typical receptacle or female contact 1 is generally of a socket type having a front and a rear U-shaped sections 12 at two opposite positions and a pair of inwardly bowed beams 11 integrally and respectively extending therebetween. As shown in FIG. 2, the disadvantage of this type prior art contact is that the pin male contact 2 may freely laterally move between this pair of beams 11.
Another type prior art female contact 3 as shown in FIG. 3 discloses a first and a second frames 34, and a base contact section 32 and a first and a second top contact sections 31, 33 oppositely extending between these two frames 34 wherein the first top contact section 31 and the second top contact section 33 side by side abut against each other to intentionally form as a unit for symmetrically and correspondingly incorporating the base contact section 32 to sandwich a pin type male contact 2 therebetween. Referring to FIG. 4, this type prior art female contact not only has the disadvantage as mentioned in the former type prior art, but also, due to manufacturing limitations, has an intention of the space "d" occurring between the oppositely facing edges of the first and the second top contact sections 31 and 33 which results in sharp corners A1 and A2 easily scratching the mating male contact 2. Thus, the first and the second top contact sections 31 and 33 do not function as a unit as originally designed to cooperate with the base contact section 32.
The third type prior art female contact as disclosed in U.S. Pat. No. 4,722,704, has two pairs of beams, each pair perpendicular to each other, for circumferentially retaining the male contact therein. Although the female contact in 4,722,704 may increase the retaining normal force and reduce the insertion force with the mating male contact, it lacks the consideration of uniform stress distribution along its length that enables a long lifetime usage and an appropriate material strength range of the female contact. Hence, this may restrain the designer from selecting an inexpensive material of the female contact to lower the product cost.
Accordingly, an object of the present invention is to provide a female contact which can not only effectively restrict the inserted male contact therein for reliable engagement therebetween, but also, at the same time, achieve a uniform stress distribution along the whole length of each beam of the female contact, thus obtaining a desired retention performance and a long lifetime of the female contact.